Why is Pluto not a planet?

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  • 3 weeks ago

    One of the reasons of the majority of scientists say, Pluto orbital around the Sun by overlapping the orbital plane of the rotation of Neptune around the Sun .,  So the problem arise on  this issue is that who came first between Neptune and Pluto before coming to be the Planets of the Solar system.

  • 4 weeks ago

    It is because "size matters". Pluto's mass is ~1/7th of our Moon. Do you really think Pluto qualifies as a planet? I don't. 

  • 4 weeks ago

    Because it 'is' a planet. A 'dwarf' planet.

  • 4 weeks ago

    It hasn't cleared 90% of it's orbital path. It's small and it's orbital path is very, very long, which means it misses a lot of things simply because the chances of something in it's orbit also falling into it's gravity well are rather small.

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  • 4 weeks ago

    Because it hasn't cleared its orbit and is unusually small for a planet.  Admitting it as a planet would also admit a large number of other bodies which are similar, such as Sedna and Eris, and there may well be other as yet undiscovered dwarf planets which are larger or more massive than Pluto.  It would result in there being a very large number of planets given the same status as Jupiter when they wouldn't even be particularly large moons.  But, there used to be a category of minor planet as opposed to major and I never understood why that was abandoned rather than just adding Pluto to the list.

  • 4 weeks ago

    There are many other bodies in the region that are the same size as Pluto or bigger. If Pluto is called a planet, all those others would want to be planets too. They would have rallies and protests and start trouble. 

  • 4 weeks ago

    Pedantry at work. It should have been grandfathered as a planet, thereby avoiding all the unnecessary controversy, which to the vast majority of people, has only served to reduce the already sagging status of astronomy.

  • Bill-M
    Lv 7
    4 weeks ago

    It is too small.   Pluto is smaller than Earth's moon.

  • Anonymous
    4 weeks ago

    In 2006, the International Astronomical Union (IAU) voted to define a planet as, 

    "A celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit."

    Two out of three ain't bad. (Missed the third one.) 

    That same year they created a new category, "dwarf planet", lumping Pluto with fellow trans-Neptunian object, Eris, and the large asteroid Ceres. In fact, blame Eris for all this. Discovered in 2005, it was large enough to be called the "tenth planet" but too small to be taken seriously by some astronomers. That led to the argument over what a planet is, and it being officially named after Eris, the Greek goddess of discord.

  • Anonymous
    4 weeks ago

    He is best mates with Mickey Mouse.

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